如果用“ ”表示氢原子，“ ”表示氧原子，则保持水的化学性质的最小粒子是（　　）

阅读短文，完成练习。

茉莉花是我喜欢的花。它很像小巧玲珑的喇叭，花瓣像喇叭口，花萼（è）像喇叭柄（bǐnɡ）。它白天总是不肯吹喇叭，这是为什么呢？哦，也许是因为怕光亮，也许是在睡懒觉，也许是因为怕吹喇叭影响我的学习。

读右图，图示岛屿南北端的直线距离约为（同一条经线上，纬度相差一度，距离相差110千米）（  ）

    You may have heard of the famous saying，"East or West，home is the best．"What does the word"home"mean to you？How do you say the word in French，in Chinese，in your language？Although people usually know what the word means，it sometimes has no exact translation．It's not surprising，because the idea of home is different from country to country，and from person to person．A home is more than a roof and four walls．It's the cooking，eating，talking，playing and sleeping that go on inside．And at home you usually feel safe and relaxed．

    Homes look different in different countries．They also have different things inside．For example，in cold northern Europe，there's a fire in the living room or kitchen and all the chairs face it．In the south，where the sun shines a lot and it's more important to keep the heat out，there are small windows and cool stone floors．

    We asked some people about their homes．

How often do people move house in your country？

    "In my country many people don't stay in one place for a very long time．They often move every ten years or so．"

—Chery，Boston，USA

What are features （特征） of homes in your country？

    "In Britain，even in town，there's always a garden．We have separate bedrooms and living rooms．But we don't often have balconies （阳台）．The weather isn't warm enough!"

—Pat，Exeter，England